Reflex Splints
Joint diseases caused by disorders in dentition closure or stress-induced parafunctions can be treated with reflex splints, which interrupt the imprinted, pathologic movement pattern. This is done by raising the occlusal position and reducing muscle activity with a bruxism splint (see Fig 11-7). Neuromuscular diseases originating from psychologic stress and parafunctions can be treated with this kind of reflex splint. These are also used for acute joint pains as immediate treatment as well as for pretreatment prior to centric relation splints (to achieve centric capability).
Relaxation/myorelaxation splints are applied in cases of muscular dysfunction, underdevelopment, and functional atrophy in individual muscle segments. This involves seeking a pain-free mandibular position that serves as an interim stage of treatment.
Suitable reflex splints include smooth appliances made of 1.0- to 1.5-mm-thick, hard or soft vacuum-formed sheets that are pulled over the teeth and fabricated for the maxilla or the mandible without occlusal guidance (Fig 11-7), as well as splints made of self-curing acrylic that have punctiform premature contact (interceptors).
The Hawley appliance is a bite plane for the maxilla that is fitted with a flat palatal occlusal plateau for the mandibular incisors. This is intended to increase the vertical dimension and achieve disocclusion of the posterior teeth. The appliance lies lingually close to the teeth and is retained with a labial bow and two wire clasps on the molars (Fig 11-8). Incisal edges and occlusal surfaces are not covered.
The labial bow supports the maxillary anterior teeth. The horizontal bite plane is so wide that slight excursive movements are possible.To treat muscular hyperactivity, the appliance is inserted for about 1 to 2 weeks to normalize muscle tone. As the muscles lengthen, a slight change in the condylar position is achieved and occlusal interferences are eliminated; overstimulation of the muscles can be reduced. Because the posterior teeth are not supported occlusally, they may overerupt, which is why the wearing time is limited to a maximum of 2 weeks.
The Sved appliance has the same function as the Hawley appliance and a similar form. It comprises a maxillary palatal plate that is held with two molar clasps (Fig 11-9). Instead of the labial bow, the plate is guided over the incisal edges of the maxillary anterior teeth to protect them against uncontrolled thrust. The bite plane is just as wide but sloped slightly lingually. The appliance is simple to fabricate and can also be inserted easily as it engages over the incisal edges of the maxillary anterior teeth.
A splint with three-point support is a Sved appliance with additional occlusal surfaces in the dorsal molar region.The purpose is to force eruption of the premolars.The plate wraps around the maxillary anterior teeth and the last molars, is held with wire clasps, and has an anterior occlusal plane as a sliding surface for the mandibular anterior teeth.
Anterior occlusal splints for temporary insertion (ie, a few hours) can be used to relax the muscles (eg, prior to intensive registration of relations) by eliminating occlusal interferences. These occlusal splints made of self-curing acrylic can be fabricated directly in the patient's mouth.
The Aqualizer is a prefabricated reflex splint filled with distilled water. This ready-made plastic sheet has water cushions on both sides acting as occlusal surfaces (Fig 11-10). Based on the principle of communicating vessels, whereby any homogenous liquid will always balance to the same level despite the shape or volume of the container, masticatory pressure is balanced with this appliance: Defective one-sided contact is prevented, and the TMJ is unloaded. The Aqualizer is an immediate splint that withstands even strong masticatory forces. The splint is made of a nylon sheet in the form of two occlusal pads filled with water, which are linked together by thin capillaries. All tooth contacts are cushioned by the water pads. The Aqualizer is available in two sizes and adapts to the dental arch on wearing.
Reflex splints are suitable neither as a pre-prosthetic measure where occlusal anomalies already exist nor as a means of producing the physiologic condylar position.They are also unsuitable for treating degenerative TMJ changes.